Hillary Clinton has a beer at Cafe Havana in Cartagena, Colombia Sunday.AFP/Getty Images

HO-TELL:The Hotel Caribe in Cartagena was the scene of Secret Service agents’ alleged sexual shenanigans with Colombian prostitutes, like these legal street walkers. (AFP/Getty Images)

HO-TELL: The Hotel Caribe in Cartagena was the scene of Secret Service agents’ alleged sexual shenanigans with Colombian prostitutes, like these legal street walkers (above). (Reuters)

The Hotel Caribe in Cartagena was the scene of Secret Service agents’ alleged sexual shenanigans with Colombian prostitutes, like these legal street walkers. (AFP/Getty Images)

The Secret Service’s seamy hooker scandal may have involved as many as 20 elite US agents — who are specifically trained to avoid such security-breach pitfalls, officials and sources said yesterday.

“Historically, we’ve heard about these ‘wheels-up’ parties when the president leaves — well, this was ‘pre-wheels down,’ ” said furious House Oversight and Government Reform Committee Chairman Darrell Issa (R-Calif.).

He vowed to have his committee probe the alleged Cartagena bacchanal that involved the agents dallying with prostitutes while in Colombia at the 33-nation Summit of the Americas, which President Obama attended.

“The investigation will not be about the 11 to 20 or more involved. It will be about how did this happen and how often has this happened before,” Issa angrily told CBS’s “Face the Nation.”

So far, 11 agents have been suspended with pay for the reported debauchery at the Hotel Caribe in the Caribbean resort town. The shenanigans came to light after one of the agents allegedly refused to pay his hooker as little as $47 for their romp — prompting a call to local cops.

The 11 agents were recalled to DC on Thursday, and a replacement team was sent in from Puerto Rico and Florida before the president arrived Friday.

“If it turns out that some of the allegations that have been made in the press are confirmed, then of course, I’ll be angry,” Obama said before returning home from the summit yesterday.

“We’re here on behalf of our people, and that means we conduct ourselves with the utmost dignity and probity, and obviously what has been reported doesn’t match up with those standards,” the president said.

Secret Service regulations do not bar its agents and uniformed officers from drinking or patronizing prostitutes — because the agency assumed it wouldn’t need to spell out such a rule, one source said.

“Common sense of what a Secret Service agent does dictates you be in complete appropriate physical condition. This shows poor judgment and [lack of] maturity,” a longtime former Secret Service agent briefed on the case told The Post.

Agency sources said hookers routinely hit on agents traveling abroad, but the supposedly top-notch government workers are trained to know that prostitutes — and booze — represent serious breaches of security. They can compromise guns and IDs, which could jeopardize the president’s safety. “You run the risk of them poisoning you, stealing your gun or identification,” a source said. “You’re approached in foreign countries by hookers, but you walk away.”

The agents dismissed from the trip were not part of Obama’s security team or the “advance” detail sent to scout a location before a presidential appearance. Instead, they were assigned to “support groups,’’ which are sent in only three or four days before a presidential visit to do things such as operate metal detectors, stand at fixed sentry posts and handle bomb-sniffing dogs.

“The advance guys work their asses off . . . But these support groups, they don’t have any real pressure on them until the president arrives,” one source said.

In a separate incident, five US military members assigned to assist with presidential security were confined to quarters for their own curfew violations.